US4426560A - Reduced pressure electrical switch - Google Patents

Reduced pressure electrical switch Download PDF

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Publication number
US4426560A
US4426560A US06/206,502 US20650280A US4426560A US 4426560 A US4426560 A US 4426560A US 20650280 A US20650280 A US 20650280A US 4426560 A US4426560 A US 4426560A
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US
United States
Prior art keywords
switch
electrical switch
hermetically sealed
switch module
contact
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US06/206,502
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English (en)
Inventor
Clive W. Kimblin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CBS Corp
Original Assignee
Westinghouse Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Assigned to WESTINGHOUSE ELECTRIC CORPORATION, A CORP. OF PA. reassignment WESTINGHOUSE ELECTRIC CORPORATION, A CORP. OF PA. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: KIMBLIN CLIVE W.
Priority to US06/206,502 priority Critical patent/US4426560A/en
Priority to CA000389155A priority patent/CA1177865A/en
Priority to GB8133212A priority patent/GB2087651B/en
Priority to IN1232/CAL/81A priority patent/IN154972B/en
Priority to DE19813144598 priority patent/DE3144598A1/de
Priority to IT25034/81A priority patent/IT1139706B/it
Priority to FR8121303A priority patent/FR2494032B1/fr
Priority to JP56181259A priority patent/JPS57109226A/ja
Publication of US4426560A publication Critical patent/US4426560A/en
Application granted granted Critical
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/002—Very heavy-current switches
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/60—Switches wherein the means for extinguishing or preventing the arc do not include separate means for obtaining or increasing flow of arc-extinguishing fluid
    • H01H33/64—Switches wherein the means for extinguishing or preventing the arc do not include separate means for obtaining or increasing flow of arc-extinguishing fluid wherein the break is in gas

Definitions

  • the present invention relates to electrical switching devices and more particularly to controlling the operating pressure of the device to minimize contact damage and erosion during the separation of the contacts.
  • the invention is applicable to a wide variety of electrical switches ranging from low voltage a.c. switch-contactors or circuit-breakers, which operate at from about 110 to 440 volts a.c., to highly specialized low d.c. voltage shunt bypass switches for electrochemical cells.
  • the preferred contact material is an alloy containing significant proportions of silver, which is a high cost noble metal. These type of switches are typically open to ambient atmospheric pressure air. Silver is used as the contact because silver forms a conducting oxide which maintains high electrical conductivity and efficient current flow through the closed switch contacts. Recent shortages of materials such as silver have dramatically increased the cost of such contacts, and it is obviously desirable to eliminate or minimize the need for high cost, noble metal contact constituents.
  • the switch In low voltage d.c. shunt bypass switches for electrochemical cells, which are operated at typically less than 10 volts d.c. with continuous current ratings of about 6,000 amperes for a single switch, the switch is typically a hermetically sealed, high vacuum device.
  • the contacts are typically copper or copper-bismuth, high conductivity material, with requisite weld-break characteristic upon switch opening.
  • the oxide of copper is a poor conductor and the vacuum condition within the switch prevents oxidation of the copper contacts.
  • the present inventor had earlier observed and reported that the vacuum-arc cathode erosion rate can be decreased by more than an order of magnitude with increasing ambient pressure, as reported in "Cathode Spot Erosion And Ionization Phenomena In Transition From Vacuum To Atmospheric Pressure Arcs" Journal of Applied Physics, Volume 45, Number 12, pp. 5235-5244 (1974), and in “Anode Phenomena In Vacuum And Atmospheric Pressure Arcs", Volume PS-2, pp. 310-319, December 1974.
  • the electrical switch devices of the present invention comprise a body portion which defines a volume within which the switching current or arc is interrupted.
  • the body portion includes a flexible portion with at least one movable electrical contact supported from the flexible body portion and is movable therewith into and away from electrical contact with an opposed electrical contact.
  • the ambient pressure within the volume defined by the body portion is maintained at or is reducible during contact opening to between about 10 -1 to 10 2 Torr to minimize contact damage and erosion during contact opening.
  • the use of expensive silver or noble metal contacts can be minimized or eliminated.
  • a hermetically sealed switch module embodiment comprises an annular insulating envelope portion, annular flexible, corrugated diaphragm members extending transversely inwardly from the annular insulating envelope portion to cylindrical conductive contact members.
  • the hermetically sealed switch module has a reduced pressure atmosphere which is maintained at from about 10 -1 to 10 2 Torr.
  • FIG. 1 is a side elevation view, partly in section of an electrical switch embodiment of the present invention.
  • FIG. 2 is a plot of the variation of cathode erosion rate in grams per coulomb versus ambient nitrogen pressure in Torr, for copper cathodes at 100 ampere and 1000 ampere arcs.
  • FIG. 3 is a schematic representation of another embodiment electrical switch per the present invention.
  • FIG. 4 is yet another switch embodiment in schematic representation.
  • the electrical switch 10 has the basic structure of a low voltage d.c., hermetically sealed, shunt bypass switch as described in U.S. Pat. No. 4,216,361.
  • a high vacuum of about 10 -4 Torr or greater is maintained in the switch.
  • the design conditions are for less than about 10 volts d.c. and about 6000 amperes continuous current.
  • This shunt bypass switch 10 comprises an annular insulating body portion 12, with annular flexible corrugated diaphragm members 14a, 14b extending transversely from the body portion to cylindrical conductive contacts 16a, 16b.
  • a hermetical seal is formed between the inner and outer extensions of the diaphragm member and the body portion 12 and the contacts 16a, 16b to define a switch volume.
  • a pair of spaced apart, angled annular arc shield means, inner arc shield 18 or outer arc shield 20, are disposed within this switch volume about the contacts 16a, 16b to intercept hot, eroded material from the contacts during arc interruption.
  • the erosion of contact material can be minimized by maintaining an ambient pressure within the switch volume which is between 10 -1 to 10 2 Torr.
  • a non-oxidizing fill gas such as nitrogen, helium, argon is preferably introduced during fabrication of the switch and pumped down to the desired ambient pressure of 10 -1 to 10 2 Torr, to minimize oxidation of the contacts 16a, 16b which could, for example, be copper or copper alloys and mixtures.
  • planar conductive mounting plates 22a, 22b connected to the cylindrical contacts 16a, 16b outside the switch volume facilitate connection of the switch to the electrochemical cell terminals or bus connectors.
  • the electrical switch 24 comprises an insulating body portion 26, an end member 28 through which fixed contact 30 extends, and a bellows end portion 32 which a movable contact 34 extends.
  • An annular arc shield 35 is disposed within the switch volume about the contacts 30 and 34.
  • the annular arc shield 35 is supported by and extends from end member 28.
  • This switch 24 can be hermetically sealed and filled to an ambient pressure within the switch of from about 10 -1 to 10 2 Torr. When the switch volume is sufficiently low relative to the bellows displacement volume the switch need not be hermetically sealed, but can utilize the bellows expansion on contact opening to reduce the ambient pressure from atmospheric to the preferred ambient pressure of 10 -1 to 10 2 Torr.
  • an inert fill gas such as argon or nitrogen at the desired fill pressure of 10 -1 to 10 2 Torr is provided.
  • the electrial contacts are then preferably oxygen-free-high-conductivity copper.
  • the inert gas fill ensure no oxidation of these contacts to keep the closed contact resistance low, and the reduced pressure minimizes contact erosion.
  • the use of copper or copper alloy contacts instead of a noble metal such as silver permits a significant material cost saving.
  • the extending ends or contact surfaces 36 associated with each contact 30 and 34 is formed of a noble metal such as silver or a high silver content alloy or compact, such as silver-tungsten, silver-cadmium oxide.
  • a noble metal such as silver or a high silver content alloy or compact, such as silver-tungsten, silver-cadmium oxide.
  • the embodiment seen in FIG. 4 is designed for higher voltage operation.
  • the electrical switch 38 includes insulating body portion 40, a centrally disposed contact 42, and bellows end portions 44, 46 at each end of body portion 40.
  • Movable contacts 48, 50 are supported respectively from bellows end portions 44 and 46.
  • a pair of series arcs are formed when respective contacts 48 and 50 are separated from central contact 42.
  • the ambient pressure in which the arcs burn and are extingushed is determined to be from about 10 -1 to 10 2 Torr.
  • FIGS. 3 and 4 can be used in medium voltage a.c. circuit breaker systems.
  • the reduced pressure within the switch minimizes contact erosion and permits use of copper or copper alloy contacts as opposed to silver contacts which have heretofore been necessary in atmospheric pressure air exposed contacts.

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US06/206,502 1980-11-13 1980-11-13 Reduced pressure electrical switch Expired - Lifetime US4426560A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
US06/206,502 US4426560A (en) 1980-11-13 1980-11-13 Reduced pressure electrical switch
CA000389155A CA1177865A (en) 1980-11-13 1981-10-30 Reduced pressure electrical switch
GB8133212A GB2087651B (en) 1980-11-13 1981-11-04 Electrical switching devices
IN1232/CAL/81A IN154972B (it) 1980-11-13 1981-11-05
DE19813144598 DE3144598A1 (de) 1980-11-13 1981-11-10 Elektrische schalteinrichtung
IT25034/81A IT1139706B (it) 1980-11-13 1981-11-12 Interruttore elettrico a pressione ridotta
FR8121303A FR2494032B1 (fr) 1980-11-13 1981-11-13 Dispositif de commutation electrique et module de commutation pourvu dudit dispositif
JP56181259A JPS57109226A (en) 1980-11-13 1981-11-13 Electric switching device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US06/206,502 US4426560A (en) 1980-11-13 1980-11-13 Reduced pressure electrical switch

Publications (1)

Publication Number Publication Date
US4426560A true US4426560A (en) 1984-01-17

Family

ID=22766686

Family Applications (1)

Application Number Title Priority Date Filing Date
US06/206,502 Expired - Lifetime US4426560A (en) 1980-11-13 1980-11-13 Reduced pressure electrical switch

Country Status (8)

Country Link
US (1) US4426560A (it)
JP (1) JPS57109226A (it)
CA (1) CA1177865A (it)
DE (1) DE3144598A1 (it)
FR (1) FR2494032B1 (it)
GB (1) GB2087651B (it)
IN (1) IN154972B (it)
IT (1) IT1139706B (it)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5191180A (en) * 1990-07-19 1993-03-02 Fuji Electric Co., Ltd. Gas-insulated switchgear including a vacuum switch, operating mechanism and plural bellows
US20050247676A1 (en) * 2002-10-29 2005-11-10 Telfer Duncan J Circuit breaker
US20090302989A1 (en) * 2006-08-10 2009-12-10 Ubukata Industries Co., Ltd Thermally responsive switch
US20090315666A1 (en) * 2006-08-10 2009-12-24 Ubukataindustries Co., Ltd. Thermally responsive switch

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3430490A1 (de) * 1984-08-18 1986-02-27 Doduco KG Dr. Eugen Dürrwächter, 7530 Pforzheim Schaltkammer fuer ein elektrisches schaltgeraet, insbesondere zur verwendung in der niederspannungs-energietechnik
DE3432025A1 (de) * 1984-08-31 1986-03-13 Kromberg & Schubert, 5600 Wuppertal Schaltgeraet, insbesondere zum ein- und ausschalten von stromverbrauchern grosser leistung
DE4020820C2 (de) * 1990-06-29 1998-04-16 Ritter Starkstromtech Kurzschließeranordnung für Hochstrom

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2326074A (en) * 1939-09-20 1943-08-03 Westinghouse Electric & Mfg Co Circuit interrupter
DE1100780B (de) * 1959-07-17 1961-03-02 Siemens Ag Kurzschliesser zur UEberbrueckung von Stoerlichtboegen in elektrischen Mittel- oder Hochspannungsanlagen
DD108407A1 (it) * 1973-12-20 1974-09-12
NL154369B (nl) * 1973-12-21 1977-08-15 Hazemeijer Bv Elektrische hoogspanningsschakelaar met twee in serie geschakelde schakeltrajecten.
US3950628A (en) * 1974-10-10 1976-04-13 Westinghouse Electric Corporation Bellows type shorting switch
ZA767617B (en) * 1976-01-19 1977-11-30 Westinghouse Electric Corp An improvement in or relating to low voltage vacuum shorting switch
DE2812987A1 (de) * 1978-03-23 1979-10-04 Tokyo Shibaura Electric Co Vakuumunterbrecher
US4216361A (en) * 1978-11-17 1980-08-05 Westinghouse Electric Corp. Low voltage vacuum switch with plural conic shields about the contacts
JPS5826132B2 (ja) * 1978-11-22 1983-06-01 株式会社日立製作所 真空しや断器
JPS5811050B2 (ja) * 1978-12-25 1983-03-01 富士通株式会社 リ−ドスイツチ

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5191180A (en) * 1990-07-19 1993-03-02 Fuji Electric Co., Ltd. Gas-insulated switchgear including a vacuum switch, operating mechanism and plural bellows
US20050247676A1 (en) * 2002-10-29 2005-11-10 Telfer Duncan J Circuit breaker
US20090302989A1 (en) * 2006-08-10 2009-12-10 Ubukata Industries Co., Ltd Thermally responsive switch
US20090315666A1 (en) * 2006-08-10 2009-12-24 Ubukataindustries Co., Ltd. Thermally responsive switch
US8902038B2 (en) 2006-08-10 2014-12-02 Ubukata Industries Co., Ltd. Thermally responsive switch
US8902037B2 (en) 2006-08-10 2014-12-02 Ubukata Industries Co., Ltd. Thermally responsive switch

Also Published As

Publication number Publication date
CA1177865A (en) 1984-11-13
JPS57109226A (en) 1982-07-07
GB2087651B (en) 1985-04-24
FR2494032B1 (fr) 1987-01-09
IN154972B (it) 1984-12-22
DE3144598A1 (de) 1982-07-15
IT8125034A0 (it) 1981-11-12
IT1139706B (it) 1986-09-24
FR2494032A1 (fr) 1982-05-14
GB2087651A (en) 1982-05-26

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